Fixtures are designed to guide and locate the moving tool and also to accommodate several assemblies according to the size of the component. The stator blade assemblies can be welded using a different way as well in which the weld procedure for each joint between blade platforms requires four weld passes: tack and finish weld for the outer platform, tack and finish weld for the inner platform. Now to do all this we need a different set of beam settings and a different pattern of movement of the workpiece manipulator. It is obvious that now the system complexity has been increased and we secondary automated support. This support comes from the CNC wherein the operator first teaches the machine about each of the subroutines for the four weld passes. He next teaches the machine as how to properly position the angle at each joint in a sequence such that when the heat distributes, the possible distortion minimize. Now as the machine is now aware as to operate the fundamentals, the operator has only to initiate the welding cycle and the machine takes on functioning by itself the operator taking on only a supervisory role.
LASER BEAM WELDING
Laser Beam welding is a welding fusion process in which materials are joined by the use of lasers. High intensity Lasers for welding generally used to join materials with high melting point like Superalloys. The laser beams in the systems are focused to the cavity of the materials and have enough energy to melt the materials and fill the cavity. This process is very helpful as it can be easily automated with robotics machinery.In the setup, there is circuit consisting of a highly charged capacitor, two high intensity flash lamps, lens and two reflecting mirrors. As in the picture, they are being set up.The energy source supply high energy and the flash lamps emits energised photons.These photons strikes on the surface of the Ruby Crystal and the electrons, due to these photons, get excited to higher shells. These electrons, when return back to lower energy states, emits photons which travels in directions. These photons again excite the electrons and same process repeats to produce two photons. This repeats and repeats and results in a concentrated photon beam. The above mirror being 100% reflective, and other partially reflective, reflects the photon and from the lower side, some photons get released to incident on the lens. The lens focus the beam to the point of cavity. This high intensity photons have energy enough to melt the material and fill the cavity. This become a strong weld when the melt freezes.
The power density is very high, in the order of 1MW/square cm. Because of this the HAZ is less and rate of cooling is high. Due to the focusing of This designing and positioning of the concentrated light beam can be automated and generally, CAM is used to control the motions.
Some salient features of LBW are:
●High quality and no electrode required
●No tool wears as it is a non contact process
●Easily automated and can be used for large scale production
●Ability to weld metals and superalloys of different physical properties
●Unlike EBW, can be done through air and no vacuum is required.
But, instead of these properties it is not used very much in daily life welding as initial
cost and maintenance cost is too high. Also, high skilled labours are required and the
energy conversion is very less.